278 lines
8.7 KiB
Nix
278 lines
8.7 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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cfg = config.security.sudo;
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toUserString = user: if (isInt user) then "#${toString user}" else "${user}";
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toGroupString = group: if (isInt group) then "%#${toString group}" else "%${group}";
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toCommandOptionsString = options:
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"${concatStringsSep ":" options}${optionalString (length options != 0) ":"} ";
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toCommandsString = commands:
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concatStringsSep ", " (
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map (command:
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if (isString command) then
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command
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else
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"${toCommandOptionsString command.options}${command.command}"
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) commands
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);
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in
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{
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###### interface
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options.security.sudo = {
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defaultOptions = mkOption {
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type = with types; listOf str;
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default = [ "SETENV" ];
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description = mdDoc ''
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Options used for the default rules, granting `root` and the
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`wheel` group permission to run any command as any user.
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'';
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};
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enable = mkOption {
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type = types.bool;
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default = true;
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description =
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lib.mdDoc ''
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Whether to enable the {command}`sudo` command, which
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allows non-root users to execute commands as root.
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'';
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};
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package = mkPackageOption pkgs "sudo" { };
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wheelNeedsPassword = mkOption {
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type = types.bool;
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default = true;
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description = mdDoc ''
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Whether users of the `wheel` group must
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provide a password to run commands as super user via {command}`sudo`.
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'';
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};
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execWheelOnly = mkOption {
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type = types.bool;
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default = false;
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description = mdDoc ''
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Only allow members of the `wheel` group to execute sudo by
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setting the executable's permissions accordingly.
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This prevents users that are not members of `wheel` from
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exploiting vulnerabilities in sudo such as CVE-2021-3156.
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'';
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};
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configFile = mkOption {
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type = types.lines;
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# Note: if syntax errors are detected in this file, the NixOS
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# configuration will fail to build.
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description = mdDoc ''
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This string contains the contents of the
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{file}`sudoers` file.
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'';
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};
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extraRules = mkOption {
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description = mdDoc ''
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Define specific rules to be in the {file}`sudoers` file.
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More specific rules should come after more general ones in order to
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yield the expected behavior. You can use mkBefore/mkAfter to ensure
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this is the case when configuration options are merged.
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'';
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default = [];
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example = literalExpression ''
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[
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# Allow execution of any command by all users in group sudo,
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# requiring a password.
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{ groups = [ "sudo" ]; commands = [ "ALL" ]; }
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# Allow execution of "/home/root/secret.sh" by user `backup`, `database`
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# and the group with GID `1006` without a password.
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{ users = [ "backup" "database" ]; groups = [ 1006 ];
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commands = [ { command = "/home/root/secret.sh"; options = [ "SETENV" "NOPASSWD" ]; } ]; }
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# Allow all users of group `bar` to run two executables as user `foo`
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# with arguments being pre-set.
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{ groups = [ "bar" ]; runAs = "foo";
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commands =
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[ "/home/baz/cmd1.sh hello-sudo"
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{ command = '''/home/baz/cmd2.sh ""'''; options = [ "SETENV" ]; } ]; }
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]
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'';
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type = with types; listOf (submodule {
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options = {
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users = mkOption {
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type = with types; listOf (either str int);
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description = mdDoc ''
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The usernames / UIDs this rule should apply for.
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'';
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default = [];
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};
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groups = mkOption {
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type = with types; listOf (either str int);
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description = mdDoc ''
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The groups / GIDs this rule should apply for.
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'';
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default = [];
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};
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host = mkOption {
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type = types.str;
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default = "ALL";
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description = mdDoc ''
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For what host this rule should apply.
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'';
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};
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runAs = mkOption {
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type = with types; str;
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default = "ALL:ALL";
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description = mdDoc ''
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Under which user/group the specified command is allowed to run.
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A user can be specified using just the username: `"foo"`.
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It is also possible to specify a user/group combination using `"foo:bar"`
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or to only allow running as a specific group with `":bar"`.
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'';
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};
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commands = mkOption {
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description = mdDoc ''
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The commands for which the rule should apply.
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'';
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type = with types; listOf (either str (submodule {
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options = {
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command = mkOption {
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type = with types; str;
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description = mdDoc ''
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A command being either just a path to a binary to allow any arguments,
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the full command with arguments pre-set or with `""` used as the argument,
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not allowing arguments to the command at all.
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'';
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};
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options = mkOption {
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type = with types; listOf (enum [ "NOPASSWD" "PASSWD" "NOEXEC" "EXEC" "SETENV" "NOSETENV" "LOG_INPUT" "NOLOG_INPUT" "LOG_OUTPUT" "NOLOG_OUTPUT" "MAIL" "NOMAIL" "FOLLOW" "NOFLLOW" "INTERCEPT" "NOINTERCEPT"]);
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description = mdDoc ''
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Options for running the command. Refer to the [sudo manual](https://www.sudo.ws/docs/man/1.9.15/sudoers.man/#Tag_Spec).
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'';
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default = [];
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};
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};
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}));
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};
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};
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});
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};
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extraConfig = mkOption {
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type = types.lines;
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default = "";
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description = mdDoc ''
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Extra configuration text appended to {file}`sudoers`.
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'';
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};
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};
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###### implementation
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config = mkIf cfg.enable {
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assertions = [ {
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assertion = cfg.package.pname != "sudo-rs";
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message = ''
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NixOS' `sudo` module does not support `sudo-rs`; see `security.sudo-rs` instead.
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'';
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} ];
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security.sudo.extraRules =
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let
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defaultRule = { users ? [], groups ? [], opts ? [] }: [ {
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inherit users groups;
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commands = [ {
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command = "ALL";
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options = opts ++ cfg.defaultOptions;
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} ];
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} ];
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in mkMerge [
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# This is ordered before users' `mkBefore` rules,
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# so as not to introduce unexpected changes.
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(mkOrder 400 (defaultRule { users = [ "root" ]; }))
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# This is ordered to show before (most) other rules, but
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# late-enough for a user to `mkBefore` it.
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(mkOrder 600 (defaultRule {
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groups = [ "wheel" ];
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opts = (optional (!cfg.wheelNeedsPassword) "NOPASSWD");
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}))
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];
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security.sudo.configFile = concatStringsSep "\n" (filter (s: s != "") [
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''
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# Don't edit this file. Set the NixOS options ‘security.sudo.configFile’
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# or ‘security.sudo.extraRules’ instead.
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''
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(pipe cfg.extraRules [
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(filter (rule: length rule.commands != 0))
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(map (rule: [
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(map (user: "${toUserString user} ${rule.host}=(${rule.runAs}) ${toCommandsString rule.commands}") rule.users)
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(map (group: "${toGroupString group} ${rule.host}=(${rule.runAs}) ${toCommandsString rule.commands}") rule.groups)
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]))
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flatten
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(concatStringsSep "\n")
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])
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"\n"
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(optionalString (cfg.extraConfig != "") ''
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# extraConfig
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${cfg.extraConfig}
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'')
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]);
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security.wrappers = let
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owner = "root";
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group = if cfg.execWheelOnly then "wheel" else "root";
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setuid = true;
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permissions = if cfg.execWheelOnly then "u+rx,g+x" else "u+rx,g+x,o+x";
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in {
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sudo = {
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source = "${cfg.package.out}/bin/sudo";
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inherit owner group setuid permissions;
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};
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sudoedit = {
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source = "${cfg.package.out}/bin/sudoedit";
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inherit owner group setuid permissions;
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};
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};
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environment.systemPackages = [ cfg.package ];
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security.pam.services.sudo = { sshAgentAuth = true; usshAuth = true; };
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environment.etc.sudoers =
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{ source =
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pkgs.runCommand "sudoers"
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{
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src = pkgs.writeText "sudoers-in" cfg.configFile;
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preferLocalBuild = true;
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}
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# Make sure that the sudoers file is syntactically valid.
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# (currently disabled - NIXOS-66)
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"${pkgs.buildPackages.sudo}/sbin/visudo -f $src -c && cp $src $out";
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mode = "0440";
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};
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};
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}
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